Bath is centred on the bottom of the Avon Valley, located at the southern edge of the Cotswolds, a range of limestone hills designated as an Area of Outstanding Natural Beauty. The hills that surround and make up the city have a maximum altitude of 238 metres (780 ft) on the Lansdown plateau. It has an area of 29 km² (11 mile²).

The surrounding hills give Bath its steep streets and make its buildings appear to climb the slopes. The flood plain of the River Avon, which runs through the centre of the city, is at an altitude of 17 metres. The river, once an unnavigable series of braided streams broken up by swamps and ponds, has been managed by weirs into a single channel. Nevertheless, periodic flooding was normal until major flood control works in the 1970s; this shortened the life of many buildings in the lowest part of the city.

The archaeological evidence shows that the site of the main spring was treated as a shrine by the Celts, and dedicated to the goddess Sulis. The Romans probably occupied Bath shortly after their invasion of Britain in 43 AD. They knew it as Aquae Sulis (literally "the waters of Sulis"), identifying the goddess with Minerva. In Roman times the worship of Sulis continued and messages to her scratched onto metal have been recovered from the Sacred Spring by archaeologists. These are known as curse tablets. These curse tablets were written in Latin, and usually laid curses on other people, whom they feel had done them wrong. For Example, if a citizen had his clothes stolen at the Baths, he would write a curse on a tablet, to be read by the Goddess Sulis, and also, the "suspected" names would be mentioned.
The corpus from Bath is the most important found in Britain.

During the Roman period, increasingly grand temples and bathing complexes were built in the area, including the Great Bath. Rediscovered gradually from the 18th century onward, they have become one of the city's main attractions. The city was given defensive walls, probably in the 3rd century. From the later 4th century on, the Western Roman Empire and its urban life declined. However, while the great suite of baths at Bath fell into disrepair, some use of the hot springs continued.

There had been much rebuilding in the Stuart period, but this was eclipsed by the massive expansion of the city in Georgian times. The old town within the walls was also largely rebuilt. This was a response to the continuing demand for elegant accommodation for the city's fashionable visitors, for whom Bath had become a pleasure resort as well as a spa. The architects John Wood the elder and his son John Wood the younger laid out the new quarters in streets and squares, the identical facades of which gave an impression of palatial scale and classical decorum. The creamy gold of Bath stone further unified the city, much of it obtained from the limestone Combe Down and Bathampton Down Mines under Combe Down, which were owned by Ralph Allen (1694–1764). The latter, in order to advertise the quality of his quarried limestone, commissioned the elder John Wood to build him a country house on his Prior Park estate. A shrewd politician, he dominated civic affairs and became mayor several times.

The early 18th century saw Bath acquire its first purpose-built theatre, pump room and assembly rooms. Master of Ceremonies Beau Nash, who presided over the city's social life from 1705 until his death in 1761, drew up a code of behaviour for public entertainments. However, the city declined as a fashionable resort in the 19th century.

Bath elected two members to the Unreformed House of Commons.

Of Bath's notable buildings, Bath Abbey is one of the most striking and whilst appearing very old, in terms of Britain's many ancient Abbeys and cathedrals, it is comparatively new. Originally a Norman church on earlier foundations, it was rebuilt in the early 16th century and transformed into a gothic fantasy of flying buttresses with crocketed pinnacles decorating a crenelated and pierced parapet. The style of architecture employed is known as late Perpendicular. The choir and transepts have a fine fan vault by Robert and William Vertue, who worked on the fan vault at King's College Chapel, Cambridge and designed similar vaulting in the Henry VII chapel at Westminster Abbey. The nave was given a matching vault in the 19th century. The building is lit by 52 windows.

The dominant style of architecture in Bath is Georgian, which is an evolution of the Palladian revival style which became popular in the early 18th century. Many of the prominent architects of the day were employed in the development of the city, and as a result Bath has many fine terraces of what appear to be elegant townhouses. However, the original purpose of much of Bath's fine architecture is concealed by the honey-coloured classical facades; in an era before the advent of the luxury hotel, these apparently elegant residences were frequently purpose-built rooming or lodging houses, where visitors to the city could hire a room, a floor, or (according to their means) an entire house for the duration of their visit, and be waited on by the house's communal servants.

"The Circus" is one of the most splendid examples of town planning in the city. Three long, curved terraces designed by the elder John Wood form a circular space or theatre intended for civic functions and games. The games give a clue to the design, the inspiration behind which was the Colosseum in Rome. Like the Colosseum, the three facades have a different order of architecture on each floor: Doric on the ground level, then Ionic on the piano nobile and finishing with Corinthian on the upper floor, the style of the building thus becoming progressively more ornate as it rises. Wood never lived to see his unique example of town planning completed, as he died 5 days after personally laying the foundation stone on May 18 1754.



The best known of Bath's terraces is the Royal Crescent, built between 1767 and 1774 and designed by the younger John Wood. But all is not what it seems; while Wood designed the great curved facade of what appears to be about 30 houses with Ionic columns on a rusticated ground floor, that was the extent of his input. Each purchaser bought a certain length of the facade, and then employed their own architect to build a house to their own specifications behind it; hence what appear to be two houses is sometimes one. This system of elegant town planning is betrayed at the rear of the crescent: while the front is completely uniform and symmetrical, the rear is a mixture of differing roof heights, juxtapositions and fenestration. This "all to the front and no rear" architecture occurs repeatedly in Bath.

Circa 1770 the eminent neoclassical architect Robert Adam designed Pulteney Bridge, using as the prototype for the three-arched bridge spanning the Avon an original, but unused, design by Palladio for the Rialto Bridge in Venice. Thus Pulteney Bridge became not just a means of crossing the river, but also a shopping arcade, and, along with the Rialto Bridge, is one of the very few surviving bridges in Europe to serve this dual purpose. It has been substantially altered since it was built. It was named after Frances and William Johnstone Pulteney, the owners of the Bathwick estate for which the bridge provided a link to the rest of Bath.

The heart of the Georgian city was the Pump Room, which, together with its associated Lower Assembly Rooms, was designed by Thomas Baldwin, a local builder who was responsible for many other buildings in the city, including the terraces in Argyle Street. Baldwin rose rapidly, becoming a leader in Bath's architectural history. In 1776 he was made the chief City Surveyor, and in 1780 became City Architect. In 1776 he designed the Bath Guildhall, where his design of the interior is reputed to be one of the finest neo-classical interiors in the country. However, it is Great Pulteney Street, where he eventually lived, which is one of his finest works: this wide boulevard, constructed circa 1789 and over 300 m long and 30 m wide, is one of England's most attractive thoroughfares, and is lined on both sides by Georgian terraces.

Architecturally, Bath is one of the most balanced cities in England, and is an unusual example of coherent town planning combined with well-executed and diverse architectural styles.